ROME, 6 November 2002 -- Desertification affects 30 percent of the earth's land surface, threatening much of the world's productive land. To deal with this critical problem, scientists are increasingly looking to Conservation Agriculture, a strategy that helps hold back the desert, raises yields, increases incomes and allows farmers to shorten fallow periods.

Recently, with the help of an FAO team led by Conservation Agriculture expert José Benites, 17 participants from 8 of the world's driest countries gathered for a course at the Extension and Experimental Station for Irrigation and Land Techniques, known by its Italian acronym of CO.T.IR. (Centro per la Sperimentazione delle Tecniche Irrigue ) on Italy's Adriatic coast. They were joined by experts from FAO and other institutions in Australia and the United States.

The purpose: hold back the desert. The means: Conservation Agriculture.

Protecting the land

Conservation Agriculture has three main principles: minimal soil disturbance and direct planting, maintenance of a permanent soil cover and judicious choice of crop rotations. It starts with low-till or no-till agriculture, which makes ploughing unnecessary. This helps maintain organic matter in the soil and decreases wind and water erosion.

"In conventional approaches, farmers till their land in order to sow seeds, but also to aerate the soil, let in water, get rid of the residues of the previous crop and expose and destroy harmful pests and organisms," explains Mr Benites. "But instead of tilling they can use seed drills - which create small pockets for seeds while leaving crop residues in place. These residues protect the land from wind erosion and promote biological activity, which aerates the soil just as well."

No-till also increases the amount of organic matter in the ground, creating a porous soil structure that allows more water to filter through to the crops' roots - instead of running off the surface, taking precious soil with it. The result is more crop and less erosion.

As for pests, they can be controlled through integrated pest management (IPM), a technique that controls undesirable organisms by exposing them to their natural enemies, minimizing the use of chemical pesticides.

The result of Conservation Agriculture and IPM is much greater resistance to environmental degradation, including wind and water erosion. Yields and incomes rise, fuel and labour are no longer needed for tilling, and flooding is reduced - indeed, long-vanished springs may reappear.

Benefits for dry areas

Conservation Agriculture is particularly useful in dry areas, where low rainfall is the main constraint to growing food, and it may help farmers to switch to more productive methods. Using Conservation Agriculture enables the soil to store more of the precipitation that falls during the fallow period, so farmers can consider more intensive crop rotations.

Non-traditional rotations being considered to exploit Conservation Agriculture in dry areas include barley, wheat, lentil and chickpea, and also sunflower, sorghum and millet -- depending on available moisture.
"Conservation Agriculture requires commitment," says FAO specialist Theodor Friedrich. "Farmers must change sowing equipment, and they may need more herbicides and pesticides for the first year or two while developing integrated pest management. But so far this technique has paid off on about 60 million hectares worldwide, much of it in the United States and South America. Some of this land was degrading fast and would otherwise be nearly useless by now."

Less has been done in the fragile dry regions of North Africa and the Middle East. It is there that Conservation Agriculture is most needed to combat desertification and increase soil moisture. But it is also the environment in which it is most difficult to apply.

Breaking a vicious circle

Leaving crop residues on the ground is crucial to this strategy.But they are often needed for other purposes, usually animal feed - especially in arid regions, where organic matter is scarce and valuable. Sheep graze on barley stubble, for example, and straw is sold as supplementary feed at lean times of year. Sometimes it is valuable -- lentil straw can cost more than grain. Saudi Arabia has even imported it.

But leaving at least some crop residues in place can still pay by slowing evaporation of precious soil moisture. This effect is increased in a dry climate because residues are slower to degrade. Not tilling also conserves soil moisture, so more organic matter is produced -- outweighing the initial loss of feed or of income from its sale.

CO.T.IR scientists, led by Dr. Michele Pisante, have proved that this equation works even in drier areas. In fact, its effects in a dry environment can be dramatic, increasing wheat yields from 0.5 to 1.5 tons per hectare. It may also be possible to grow crops annually instead of every two years in areas with less than 200mm annual rainfall. Some areas could produce a crop every two years instead of every six or seven. And Conservation Agriculture can offer many ways to save soil, water, energy, labour and wear and tear on equipment.

"The participants came away from the workshop encouraged and impressed," says Dr Benites. "There are no miracles -- Conservation Agriculture requires care and work, especially in dry areas. It can hold back the desert -- and it can also make it possible to grow more food. Things don't get much better than that!"